Research purposes: Based on the introductions to the applicable research and experiences of exterior- protected construction for Metro stations，the exploration and innovation of design concept are made for the purposes of security and reduction of cost.
Research methods: Based on the construction practice and the surrounding environmental and hydrological conditions of construction, the deep explanations are given to the forms of exterior-protected construction for Metro station and its construction technology, and the analyses are made for the comparison of support form of fender post alone and soil-nailed wall with the combined forms of fender post.
Research results : In the phases of excavation of foundation pit and construction of the main body of station , the fender for the foundation experienced the tests of time and bad weather. Through making measurements to the foundation pit, the displacement of foundation pit and surface subsidence were in the range of control values，which showed foundation pit is in the safety.
Research conclusions: If the geologic and surrounding environmental conditions allow, what can be done for supporting foundation pit is that the top of foundation pit is supported by soil-nail and the bottom is supported by raw piles plus interior support or stressed anchors, so it is helpful for excavation and movement of earth, enhancing utilization of machinery, speeding up the construction process and saving cost. In the course of design, the design parameters should be modified on time in accordance with the geological survey report，soil characteristics, theoretical analysis results , experience of similar construction and measurement results.
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